Try this investigation to get learners talking about density and the mass of sugar dissolved in their favourite drinks

This resource is also available in Welsh and Irish

This experiment focuses on the mass of sugar dissolved in fizzy drinks and how this affects whether fizzy drink cans float in water. First watch the video showing the ‘heavy sugar’ demonstration, then find out how your learners can explore the mass of sugar in their favourite fizzy drinks.

Learning objectives 

  • To recognise that objects float at different levels in relationship to their mass/density.
  • To know that mass is the measure of the amount of matter from which the object is formed and is measured in grams.
  • To understand that density is a measure of the amount of mass in a certain volume.
  • To understand the role of sugar in health.

Enquiry skills:

  • To predict, observe, and evaluate an investigation giving reasons for any explanations.

Watch the video

The video below shows how to carry out the ‘heavy sugar’ demonstration.

Source: Royal Society of Chemistry

Investigate the amount of sugar in a soft drink by comparing its weight with a diet drink.

Download the supporting materials

Set up and run the investigation with your class using the teacher notes and classroom slides, featuring a full equipment list, method, key words and definitions, questions for learners, FAQs and more.

Teacher notes

PDF | Editable Word document

Classroom slides

PDF | Editable PowerPoint document


What do learners need to know first?

Learners should understand that objects float or sink depending on their density (how much material mass is found in a certain volume) and whether this is less than the surrounding liquid (it will float) or greater than the surrounding liquid (it will sink).

They should be familiar with states of matter – the basic properties of solids, liquids and gases.

Equipment list

  • Can of diet cola
  • Can of cola (preferably same brand as the diet)
  • Plastic transparent cup
  • Teaspoon
  • Granulated sugar
  • Balance for weighing (optional)
  • Tank two-thirds full of water
  • Other types of soft drinks

Additional resources